Xfluio - -fuel burner control system



Jan; 22, 1957 T. J. DAVIDSON FLUID FUEL BURNER CONTROL SYSTEM Filed Jan. 26, 1954 BY M/ INVITFNTOR. 7750mm; J Davcdson.

ATTORAZ'Y United States Patent FLUID FUEL BURNER CONTROL SYTEM Thames "J. Davidson, Lbs Angela's, Califi, ,as signor to Robe'itsliaw Eiilton 'coiit ols Company, Greensburg, Pa.,a coi'poi'afiondfDelaware ApplieafionJaxiuary 26,1954, Seiial N0.*406,'147

Teams. ((11. 158435 This invention relates to fluid fuel burner control systems and more pafticularly to gas burner control systems which include a main burner, -a pilot burner, a main valve, and a safety valve, as well as means responsive to a 'ilame at the .pilotburner for so controlling the operation of the, safety valve as to prevent passage of gas to the main burner unless a flame is -presentat the pilot burner.

A-syst'em of this character finds particular utility in the control of the burner of a heating appliance such as a gas range which includes a main manually operable or remotely controlled valve Upon opening of the main valve, gas is supplied only to the pilot burner where it is ignited by suitable means such as an electrically heated catalyticigniter. Following ignition of the pilot burner and after an interval sufficient for heating of the flame sensitive element of the safety valve by the pilot flame, the safety valve opens automatically to permit flowof gas to the main burner where i t is ignited by the pilot burner. When, to discontinue th e heating operation, the main valve is closed,--fiow of fuel to both the main and pilot burners is terminated so that the foregoing procedure must be repeated to reestablish flame at the main burner.

The flame sensing element of the safety valve may comprise an expansible bellows for actuating the valve with a bulb positioned adjacent the pilot burner and communicating with the bellows through a capillary tube, the bulb containing asuit'able thermal, fluid which will expand upon heating toexpand the belloyvs and open the valve.v Since heating of the bulb after the pilot flame is establishedandcooling of the bulb after the pilot flame is extinguished will' require a certain amount of time for heat transfer, there is a delay period subsequent to the closing ofthemain valveand resultant termination of fuel flow to the pilot burner during which period the bulb is stillwarm and the safety valve remains open.

If, during such delay period, the main valvehis reopened, fuelwillflow to'both-the main andpilot burners so that it accumulates-in'the-oven and an explosion may occur when the pilotburner is relighted by the ignition means. M h

To; eliminate the danger pointed out above, it is an object of thisinvention to sustain aflame at'the pilot burner duringsuch delayzperiod, the flame being made small enough tobe inefiectiveto heat'the flame sensing element butbei-ng-available to efiect-reignition "of the main burner in-the-eventof reopening-of the-mainvalvel Another object of the invention is to'supply fuel to the pilot burner atarelatively high initial rate to facilitate ignition and assure rapid heating of the thermal sensing elementu-ponpeningrof-the-main valve with subsequent reductionof the fuel-- flow to an intermediaterate' 'suflicient to maintainthe-required-normal operating temperature of the thermahsenis zl element;

In a preferred embodiment'of-the inventi'o'mthe' abo've objects are accomplished-through theprovision of avplu- 2,778,416 fte ee ia;e?

at least one of the c0ndiiits s'iipplyihg alimitd amount of fuel and remaining in communication 'with the pilot burner as lo'ngas the mainlburhr safety valve remains p i v. t,

Other objetsand advantages will appear from the following specification "taken in 'c'ohiiectio'n with the accompanying drawing which a schematic View of a control system for a fuel Burneren'ibodyih'g this invention, a'portion thereofbeiiig shown in section. I j

Referring to the drawing, the control system isfsh'fown a's a'ssociatedwith a main burner 10 which receives fuel from a supply manifold 12, flowof fuel from the minifold E2 to theimaifl Burnet- I0 beiiig uhder the central of two valve means: "h ffifs't thermally responsive valve means 14, and main vialve iheaiis 15 here Shawn maniially operable but which maybe remotely controlled if desired.

lgnition 'nieahs, here shown as air electrically ihe ated catalytic "igniter 20; is diispds e'd in igniting 'relatio' [with the pilot burner 22 whi'ch 'is 'in turn disposed in igniting relation with the main burr'ije'r 10. The pilot 'burher 22 is 's'upplid with fuel through a "he: supply "c'bhduit 24 connected therewith, flow or the n the conduit 24 beiiig controlled -by a plurality of means to be more fully described hereinafter. r i I A casing 26 contains the thermally responsive a means 14 which may dompi'ise valve chamber 28 to rnd in the casing 26' and provided withf a' and an outlet opening 32. The outle municates with amai'n supply conduit 34 c main burner, 10. Disposed in the valve' 'chamber a valve seat 36coop erable a first' valve htemhi 38 to interrupt flow between theinle't 3:0 and the outlet 32. A coil spring 40 acts between a wall 126T the valvechalhber 2S and the valve member 3'8 to bia s the valve member as into engagement with the valve seat 356; p l v Dep'endin'g'from thelow'r sheer the valve hle'lhh'et 31s is aflvalve stem 44 whieh'exch s slidably t rough a bore 46 in the casing 25. The f're' end 48' of the valve steal 44 extends beneath the cafsiiig"26 to abate ye'r 5llwl'1ich is pivoted at one end 52 in a bracket'54 secured to the casing 26. v s v .f v

The lever fill is'adaptdtd be moved about its pivot by a thermally responsivetievi'ce which' may comprise all expansible element 56" communicating with; a bulb, 58 through a capillary tube 60'. The bulb 58 contains a suitable thermalflu'id' which, wheh heated, will increase the pressure Within the exp'ans'ible len'ientifitojeirpaiid the same; Thebulb 58 isidi'spo'sed adjacent the i161: burner 22 to bje 'heatedlby' a' flame emanating therefrom.

The expansible elment56 is'jmou'ntedl on 5 warez secured to the lower side of'tlie'casing zti ahd movement is transmittd'fro'm th expafisible'elenient 56 as the le'vi 50 by means of athru'st'buttohlodcarried on" the upper surface of the expansible element and abutting the'lever 50. It will be apparent that in" the absence of ,a flame at the 'pilot burhe'r'ZZA the expahsible elementjfi will be in its contracted conditioh: aiid the spring All Willhold the valve member 3a against thevalvejse'at 36'. It will also be apparent that a fi'ajrhe'rhah fihg;hem; the" bu'r'ner 22 willbe'eife'ctive to heat thehiilb 5s cduslhg expansion'ofthe exp'ansible "eiehiehts s'; counterclockwise rotation of the lever 50 and movement of the'valve mihber 38 against the bias of thesprihgm to establish communication betweentheinlffil" and outlet not the valvemeans' 14. However, after the" pilot flame is. ex'; ting'iiished, a period of'timet'riust mes-shin elapse before the bulb' 5s coolssufiiciently'to cause eohtr'actibh if the expanible element St'iahd i H i valve member 38 intoenga r in n1 Fuelis supplied'to the inlet 30 ofthevalve mearis through a firstco'nduit 66"wliich' is coi'inected to the arrears manually operable valve means 16. The manually operable valve means 16 may comprise a simple gas cock (not shown) adapted to receive fuel from the manifold 12 through a suitable connection 68.

The outlet of the manually operable valve means 16 is also connected to the pilot burner conduit 2d through a connection 70 and a cross 72. Flow control means, such as a needle valve 74, is interposed in the connection 70 to limit fuel flow from the manually operable valve means 16 to the cross 72. The manually operable valve means 16 thus controls the flow of fuel to both the thermallyv responsive valve means 14 and the pilot burner 22.

Fuel will be supplied to the pilot burner 22 through the connection 70, cross 72 and conduit 24 as long as the manually operable valve means 16 is open. However, it is desirable to maintain a supply of fuel to the pilot burner 22 as long as the thermally responsive valve means 14 is open regardless of the condition of the manually op erable valve means 16. To this end, a second conduit 76 is provided to supply stand-by fuel directly from the manifold 12 to the cross 72 under the control of second thermally responsive valve means 80.

The valve means 86 may comprise a valve chamber 82 formed in the casing 26 and provided with an inlet 84 and outlet 86. The inlet 84 communicates with a bypass conduit '78 which is connected to the manifold 12 and the outlet 86 communicates with the second conduit 76 which is connected to the cross 72. A valve seat 86 disposed in the valve chamber 82 is cooperable with a second valve member 90 to interrupt flow between the inlet 84 and outlet 86.

A spring 2 acting between the casing 26 and the valve member 96 serves to bias the valve memberttl toward the valve seat 38 and a valve stem 94 extends between the valve member 90 and the lever 50 of the thermally responsive actuating device. It will be apparent that rotation of the lever 50 under the influence of a flame at the pilot burner 22 will cause an upward movement of the valve stem 94 to move the valve member 9% away from the valve seat 88. When the valve member 9% is not so moved, it will be held against the valve seat 88 by the spring 2 to prevent fuel flow between the inlet 34 and the outlet 86.

Flow control means, here shown as a needle valve'96,

rate exceeds that required for steady state operation so that the rate of fuel flow to the pilot burner is preferably reduced subsequent to ignition of the pilot flame. Accordingly, means is provided for supplying additional fuel to the pilot burner prior to ignition and comprises a third conduit 98 and a fourth conduit ltlt connected to the conduit 66 and to the cross 72 respectively and communicating with each other through third thermally responsive valve means 102.

The thermally responsive valve means 102 comprises a valve chamber 104 formed in the casing 26 and provided with an inlet 106 and an outlet 108. The inlet 166 communicates with the conduit 98 and the outlet 1% communicates with the conduit 100. A valve seat 110 disposed in the valve chamber 104 is cooperable with a third valve member 112 to interrupt fuel flow between the inlet 106 and outlet 108.

A spring 114, acting between the valve seat 110 and the valve member 112 acts to bias the valve member 112 away from the valve seat 110 and a valve stem 116 extends between the valve member 112 and the lever 50 of the thermally responsive actuating device. It will be apparent that rotation of the lever 50 under the influence of a flame at the pilot burner 22 will cause upward movement of the valve stem 116 and associated valve member 112 to move the valve member 112 into engagement with 4 the valve seat 110 and prevent fuel flow between the inlct and the outlet 168. When the valve member 112 is not so moved, it will be held away from the valve seat til by the spring 114 to permit fuel flow.

Flow control means is provided for limiting fuel flow the conduit 10% and is here shown as comprising a needle valve 118 disposed therein.

it will be apparent that the cross 72 connects a plurality of conduits with the conduit 24 and pilot burner and the various valves hereinbefore described act to ly establish communication between such conduits and the manifold 12 to thereby control the rate of fuel flow to the pilot burner 22. The coaction between these valves and conduits will be brought out more fully in the description of the operation of the system which follows.

Assuming that the apparatus is in the condition shown in the drawing with no flame existing at any of the burn ers is desired to place the burner 10 in operation, the manually operable valve means 16 is moved to open position to permit fuel to flow through conduit 66 to the first thermally responsive valve means 14 and to the pilot burner 22 through the needle valve 74, connection 70, cross '72 and conduit 24. Fuel will also flow from the conduit 66 through conduit 98, third thermally responsive valve means 102, conduit 100, needle valve 118 and cross 72 to conduit 24 and the pilot burner 22. Thus the rate of fuel flow to the pilot burner 22 will be equal to the total amount of fuel which can be passed through the needle valves 74 and 118.

Fuel flowing from the pilot burner 22 will impinge upon the igniter 2b to cause ignition and establish a flame at the pilot burner 22. The needle valve 118 is preferably set to permit a relatively high fuel flow rate to assure easy ignition and establish an initial flame at the pilot burner of substantial size which will heat the bulb 5d rapidly as possible.

When the bulb 58 is heated, the thermal fluid contained therein will expand to cause expansion of the expansible element 56 with consequent counterclockwise movement of the lever 50. As the lever 50 is moved about its pivot, the valve members 38, 90 will be moved away from their respectix e seats and the valve member 112 will be moved into engagement with its seat.

Movement of the first valve member 38 away from its seat will establish communication between the inlet 30 and outlet 32 of the valve means 14 to supply fuel to the main burner 10 through the conduit 34. Fuel flowing from the main burner 16 will be ignited by the flame at the pilot burner 22.

Movement of the valve member 90 away from its seat will establish communication between the inlet 84 and outlet 86 of the valve means and will permit fuel to fiow through the second conduit 76 to the cross 72 thence to the pilot burner 22 through the conduit 24.

Movement of the valve member 112 into engagement with its seat will terminate fuel flow to the conduit 100. Thus, in the heated condition of the bulb 58 and open position of the valve means 16, fuel is supplied to the pilot burner 22 through the connection 70 and second conduit 76 which communicate with the pilot burner 22 through the conduit 24 and cross 72. Accordingly, under such conditions, the rate of fuel flow to the pilot burner 22 is the sum of the fuel rates which are passed by the needle valves '74 and 96. The needle valve 96 is preferably set to pass a volume of gas somewhat less than that passed by the needle valve 118 so that the pilot burner will be supplied with fuel at an intermediate rate in the heated condition of the bulb 58, such rate being sufficient to provide a flame large enough to assure maintenance of the heated condition of the bulb 58 as well as ignition of fuel flowing from the main burner 10.

In the event the manually operable valve means 16 is closed While the apparatus is in steady state operating condition and then is reopened before the bulb 58 has n ection" :70 so that no. fuel belsuppliedf to the main burner lllfor to the cross72 througlith'cvalve' 16. However; fuel will'be continued to nesuppuea to' the pilot burner 22 through the bypass conduit 78, valve means 80, conduit 76, cross 72 and. conduitll. The rate of such pilbt' fii'el' new will be d termin d" by the needle valve 96 and'is' preferably small eriough to'prevent heating of the bulb 58 so that the same may .0001 but which i'sflsufiicientto' assure the maintenanceaof a flame at' tlie pilot burner and thus assure immediate ignition of the main burner 10 upon reopening of the manually operable valve 16.

In the event the manually operable valve 16 is closed and is not reopened, the bulb 58 continues to cool until the thermal fluid therein contracts to cause contraction of the expansible element 56 and clockwise movement of the lever 50. Such movement of the lever i) permits movement of the valve members 33, 90 under their respective biases into engagement with their seats and movement of the valve member 112 away from its seat so that the apparatus is restored to its initial condition as shown in the drawing. It is to be noted that when the various parts of the apparatus are so returned to their initial positions, flow of all fuel to the pilot burner 22 is prevented and the flame at the same is extinguished.

It will be apparent from the foreging that the herein disclosed apparatus provides a control system for fluid fuel burners wherein a single pilot burner may be provided with a number of different rates of fuel flow to produce an exceptionally fast acting and safe control and that it accordingly accomplishes the objects of the invention.

Although a specific embodiment of the invention has been shown and described, it will be apparent that many modifications may be made by those skilled in the art. Such modifications may be made in the details of construction and arrangement of parts without departing from the scope of the invention as set forth in the appended claims.

It is claimed and desired to secure by Letters Patent:

1. in a control and ignition system for a main fuel burner having a source of fuel supply, comprising a single pilot burner for igniting the main burner, a first valve means operable for controlling fuel flow to the main burner and being biased 'to a fiow preventing position, r

a second valve means operable for controlling fuel flow to said pilot burner and being biased to a flow preventing position, a third valve means operable for controlling fuel flow to said pilot burner and being biased to a flow supplying position, thermally responsive means located to be heated by said pilot burner, main valve means operable for controlling fuel flow to said main burner through said first valve means and to said pilot burner through said third valve means, a pilot supply conduit and a connection from said main valve means direct to said pilot burner for augmenting the fuel flow thereto from said third valve means when said thermally responsive means is heated below a predetermined temperature, flow control means in said connection, means operatively associated with said thermally responsive means for operating said first and second valve means to flow supplying position and said third valve means to flow preventing position when said thermallyresponsive pass conduit whereby the heat of said pilot' burnen is inmeans is heated to said predetermined temperature, said pilot burner thereby being supplied with fuel through said second valve means and said pilot supply conduit, and flow control means cooperable with said second valve means and cooperable with said flow control means in said connection for reducing said fuel supply to the pilot burner but in an amount sufficient to maintain heating of-said thermally responsive means to said predetermined temperature: Q

2i Ina contraband ignition system aSjcIaimedf'mLcIam l wherein a bypass conduit is"provided for said: second valve means around said mean valveme'ans for supplyir'igffuel'to said pilotburner'indepehdentlyofsaid main valve means while said thermally responsive; means remains heatedtos'aidpredeterminedtemperature, said flow contrel"meansieoeperaule with said second fvalve means be ing'ipositioned'for'conti'olling the fuel supply insa'idbysufficient to maintain said predetermined temperature when said" main valve means remains in a fl ow preventing position for a predetermined period:

3. In a control and ignition system for a main fuel burner having a source of fuel supply, comprising a single'pilot burner for igniting the main burner, a first valve means having inlet and outlet openings and a first valve member biased for preventing flow through said openings, a main supply conduit connecting said outlet of said first valve means to the main burner, a first conduit connecting said inlet of said first valve means to the source, a second valve means having inlet and outlet openings and a second valve member biased for preventing flow through said openings, a bypass conduit connecting said inlet of said second valve means to the source, a pilot supply conduit connected to said pilot burner, a second conduit connecting said outlet of said second valve means to said pilot supply conduit, a third valve means having inlet and outlet openings and a third valve member biased for supplying fuel through said openings, a third conduit connecting said inlet of said third valve means to said first conduit, a fourth conduit connecting said outlet of said third valve means to said pilot supply conduit, thermally responsive means located to be heated by said pilot burner, and means operatively associated with said thermally responsive means for operating said first and second valve members to flow supplying position and said third valve member to flow preventing position when said thermally responsive means is heated to a predetermined temperature.

4. In a control and ignition system for a main fuel burner having a source of fuel supply, comprising a single pilot burner for igniting the main burner, a first valve means having inlet and outlet openings and a first valve member biased for preventing flow through said openings, a main supply conduit connecting said outlet of said first valve means to the main burner, 21 first conduit connecting said inlet of said first valve means to the source, a second valve means having inlet and outlet openings and a second valve member biased for preventing flow throughsaid openings, a bypass conduit connecting said inlet of'said second valve means to the source, a pilot supply conduit connected to said pilot burner, a second conduit connecting said outlet of said second valve means to said pilot supply conduit, 21. third valve means having inlet and outlet openings and a third valve member biased for supplying fuel through said openings, at third conduit connecting said inlet of said third valve means to said first conduit, a fourth conduit connecting said outlet of said third valve means to said pilot supply conduit, thermally responsive means located to be heated by said pilot burner, main valve means operable for controlling fuel flow to said main burner through said first conduit and to said pilot burner through said third conduit, said pilot supply conduit being connected from said main valve means direct to said pilot burner for. augmenting the fuel flow thereto from said fourth conduit when said thermally responsive means is heated below a predetermined temperature, and means operatively associated with said thermally responsive means for operating said first and second valve members to flow supplying position and said third valve member to flow preventing position when said thermally responsive means is heated to a predetermined temperature.

5. In a control and ignition system as claimed in claim 4 wherein flow control means are cooperable with said second valve means for reducing said fuel supply to the pilot burner but in an amount suificient to maintain heating of said thermally responsive means to said predetermined temperature.

6. In a control and ignition system as claimed in claim 5 wherein separate flow control means are located for controlling flow from said third valve means and said main valve means respectively to said pilot burner, said flow control means for said main valve means being adapted for maximum fuel flow to establish a high initial flame at said pilot burner.

7. In a control and ignition system as claimed in claim 6 wherein said flow control means cooperahle with said second valve means is adapted for lesser fuel flow than that of said flow control means for said main valve means but being suflicient to maintain said flame and said predetermined temperature of said thermally responsive means.

References Cited in the file of this patent UNITED STATES PATENTS 

